Electromagnet device



Jan 21, 193% A. N. VAN NOSTRAND 1,744,346

ELECTROMAGNET DEVI CE Filed May 26, 1925 N Lil.

INVENTOR BY M M @LLH A TTORNEYS' Patented Jan. 21, 1930 UNITED STATES PATENT OFFICE ABLE-1GB N. VAN NOSTRAIID, OF FLUSHING, NEWtYORK, ASSIGNOR TO TELAUTOGBAPH CORPORATION, OF RICHMOND, VIRGINIA, A CORPORATION OF VIRGINIA ELEG'IROMAGNET DEVICE Application filed Kay 26,

This invention relates to improvements in electro-magnet devices.

The object of the invention is to provide an electro-magnet device of the solenoid type 5 which, while showing a good electrical stroke, a quick reduction in pull toward the end of the stroke and a remaining pull at the end of the stroke sufiicient to hold the cores or plungers and any mechanism attached thereto in the desired final position against the action of any exterior force such, for example, as gravity or springs.

An electro-magnet device made in accordance with the present invention is particularly suitable for feeding or advancing a strip of material, such for example, as feed.

ing a paper record strip in a telautograph. apparatus.

The invention will be described more specifically in connection with the accompanying drawings, showing a paper strip feeding mechanism, for telautographs embodying the invention.

In the drawings;-

Figure 1 is an elevation, partly in section,

showing the plungers or cores in their retracted position, the circuit for energizing the coils being merely diagrammatic.

Figure 2 is a sectional view at right angles to Figure 1.

Figure 3 is a detail view of the armature and its attached parts.

Figure 4 is a detail perspective view of a spring switch device which may be operated by an electro-magnet device embodying the invention.

In the preferred embodiment of the invention, two solenoid coils A, A, are employed, each of which is arranged to be energized by an electric current. In the present example, the coils are included, in series, in an electric circuit, which may be energized from any suitable source. For the present purposes of explanation the circuit is shown in Figure 1 p as a simple circuit arranged to be opened and 1925. Serial No. 32,905.

closed by a switch 1, this circuit including a battery 2.

Each of the coils, A, A, is mounted on a tube 3, 3, of suitable material, preferably non-magnetic. In practice, tubes of brass are employed. Within these tubes, the solenoid cores or plungers,B, B, can slide in the direction of their longitudinal axes. Each core has one end tapered, as will be clear from the drawings. The slope and length of this tapered portion is of considerable importance. The length of the tapered portion must be greater than the desired stroke of the cores. Also it must not be less than the maximum diameter of the core and not more than 1 times said diameter. The slope should not be substantially less than 5 degrees nor more than 15 degrees.

The two cores or plungers are longer than their coils and have their respective outside ends connected by anarmature C whose crosssectional area is sufficient to give a path of good permeability for the flux, while at the same time the cross-section is relatively thin in the direction of the longitudinal axes of the cores. Therefore, to obtain the desired cross-sectional area, the armature is made relatively wide, its width being greater than i1;he diameter of'the cores and its thickness ess.

Where the electro-magnet device is used to shift a strip of material the armature C may be provided with a shunt magnetic circuit having an air gap, the arms of the shunt, in the example illustrated, being indicated at 4, 4, with an air gap at 5. Thisshunt magnetic circuit with agap may be used to actuate a subsidiary armature of magnetic material, as for example, a clamping armature indicated at D, which may be used to clamp the strip material so that, as the plungers move, the strip material will be moved with them. I As shown in the present example, the clamping armature D consists of a disk supported on a pin 6 passing through the center of the disk, this pin being carried by a guidebar 7 attached to and extending above a guide-plate 8 secured to the armature C. The guide-bar is recessed to receive the disk, as will be clear from Figure 3. The guideplate and guide-bar are made of non-magnetic material and are arranged to provide a guide-plate 8 is of metal having a co-efiicient' of expansion the same as that of the armature. In practice it has been found that Monel metal most nearly meets the requirements. Thus any warpm of the plate due to thermal changes is avolded. The clamping armature D will serve to clamp the strip of material against the poles 4, 4, when the armature C is energized and to release the strip when said armature is de-energized, thereby allowing the armature C to move without moving the strip of material.

For ease in introducing the strip of material through the guide slot 9, the guideplate 8 may be provided with a guide-lip 8' arranged at an angle, as shown in Figure 2. In this view the dotted line Z indicates the strip, which in a telautograph will be a strip of paper leading from a suitable roll, not shown, and assumed to be advanced in the direction of the arrow 2, Figure 2. It is convenient, also to so mount the disk, D, that in its non-energized position, it will tend to assume an inclined position, as indicated in Fi ure 2, thus making it easier to insert the end of a strip of paper through the guide slot 9. To accomplish this result, the disk may have its central "opening which receives the supporting pin countersunk on its side facing the armature so that when releasedby the armature, the weight of the disk will tend to tip it to the desired incline. Furthermore, owing to this incline the edge of the disk nearest to the paper comes into contact with it first when the disk is drawn up and thereafter the disk swings into full bearin on the paper so there is no sudden slam of the disk against the paper, and consequently no noise in clamping'the paper.

The electro-magnet device also comprises a yoke E which is provided with openings, one for each plunger, into which openings the inner ends of the respective plun ers may move, the said openings being in alignment with the plungers.

The yoke has a crosssectional area, intermediate the openings, which is not less than the maximum cross-sectional area of the requisite plunger made of material of high permeability and in practice may be and ad vantageously is from 1 to 2 times that of such a plunger.

Furthermore, that dimension of the crosssection of the yoke which extends parallel to the longitudinal axis of the plungers is at least as great as the diameter of such a plunger, and advantageously is greater. In practice it has been found that said dimension may be from 1 to 1 of 1 times the maximum diameter of such a plunger. By making that dimension of the yoke which extends in a direction parallel to the longitudinal axis of the plunger, of a size not less than the maximum diameter of such a plunger, B or B, and tapering the lunger ends to a sufficient extent, while a so arranging them to move into the openings in the yoke, an important effect on the action of the plungers 1s obtained, in that a longer stroke is made possible by keeping up a strong pull until toward the end of the inward stroke of the plungers, whereupon the pull rapidly decreases until at the end of the stroke the remaining pull is only sufficient to hold the plungers stationary.

In order to limit the movement of the plunger and armature C, a suitable means for limiting the play of the plungers within their coils is provided. In the direction in which the plungers move when drawn into the coils, their motion is limited by a yielding stop means. In the present example, this comprises a pad 10 of felt which rests upon the of the invention this stop mechanism is ad-.'

justable. It comprises a single rod 11 screw threaded into the yoke E, the rod extending through the armature and guide-plate and be-- ing provided with a head 12 outside the guideplate. By means of the head, the roll 11 may be turned to screw it in or out with relation to the yoke E. There may be a locking screw g 13 provided in the yoke'to engage and lock the rod 11. g

In the best embodiment of the invention the side of the guide-plate next to the head of the rod 11 carrles a projection, such as a boss 14, through which the rod 11 passes, this boss being of non-magnetic material and secured to the guide-plate, as for example, by soldering or riveting or both. The outer side of the boss 14 is provided with a recess which, advantageously, has its inner wall coned. The rod 11 is provided, next to its head, with one or more washers 15 of yielding material arranged to be squeezed between the head 12 and theiconed walls of the boss 14, thiieby stopping the plungers and armature.

n the rod 11 is so located axis coincides with the longitudinal axis through the center of gravity of the plungers and armature, and armature 'are stopped in their outward movement by the head 12 of the rod, there will be no tendency of the plungers to swing laterally in their respective tubes 3, 3.

the best embodiment of the invention that its longitudinal so that when the plungers The electro-magnet device may be provided with means for support it in a suitable manner. In the example 5 own, the yoke is carried by an arm F extending from a plate f, which may be secured to a suitable wall, post or the like, as for example, the slab of slate or the like indicated at G.' The arm F may be integral with the yoke and may have reinforcing ribs, as indicated at f, and also ma have a centrally arranged bracing web or ange F.

This web or flange serves not only to brace the arm F from the platef, but also serves as a support for a contact device to be operated by the electro-ma et device if desired, as more fully explaine hereinafter.

It will be noted that the apparatus is so constructed. that even in their extreme outward osition, the plungers B, B, extend throng the coils for substantially the entire length of each coil, so that when the coils are energized there is a strong magnetic pull and,

because of the relatively great depth or thickness of the yoke and the slope and length of taper of the core ends the ull on the plungers is maintained nearly uni orm until the inner ends of the plungers approach the outer face of the yoke, whereupon the pull falls rapidly so that when the plungers are stopped at the end of their inward stroke, the remaining pull of the plungers is just sufiicient to hold them in place. lln the embodiment of the invention shown in the drawingsfihe plungers are assumed to be vertical, and with such an arrangement, they would move outwardthat is, downward-by gravity. In such an arrangement of the apparatus, the remaining pull of the plungers at their extreme upward position is sufficient to overcome the action of gravity on the plungers and their attached arts. P In practice, the plungers are stopped slightly before their inner, or upper, ends reach the plane of the outer or upper face of the yoke. It will be observed that because of the solid armature connection between the two outer ends of the plungers a good magnetic circuit is provided, the magnetic circuit being closed at all points except between the inner ends of the plungers and the yoke, so that by the proper taper of the plunger ends and by the use of a deep yoke, the desired results are obtained.

When the electro-magnet device embodying the invention is used as a paper-shifter for telautographs, the coils A, A, are included in a local circuit, which may be closed by a relay in one of writing line circuits, so that-a strong current may be supplied to energize the said coils A, A, thus giving a relatively powerful stroke for feeding the paper strip.-

With such an electro-magnet device, it becomes possible to use the paper shifter magnets to operate certain contact devices for closing and opening other circuits of the telautograph system. The advantage of this is that the momentum of the plungers and their attached parts insures the pro or action of the circuit closer and allows t em to be made more rugged than where only a light relay is used.

In an apparatus embodying this feature of the invention the armature is provided with a post 16 carryinga roller 17 which may be revolubly mounted on a pin 18, in the present example shown as a screw which is threaded into the post. The roller 17 is arranged to be forced between a pair of outwardly flared or sloping jaws 19, 19, each carried by a central spring H, H. These springs may be secured to, but insulated from, the web or flange 7". The electric circuit to be closed and openedat the contact springs has its terminals connected to the respective contact springs. When the electro-magnet device is energized the roller 17, which is of conductive material, enters between and makes contact with the jaws 19, 19, of the two springs H, H, thereby closing the circuit. At the same time, they tensionof said springs is sufiicient to cause some friction against the roller 17 thereby assisting in checking the inward movement of the solenoid plungers B, B. Thus the contact springs serve as brakes as well as circuit closing devices.

In the embodiment of the invention illustrated in the drawings, two circuits may be controlled at the contact device. Where this is to be done, the flange f supports a third contact spring K and a rigid abutment device or stop L, these being insulated from the other springs. The contact spring K and the contact spring H may each be provided with contact points, which contact with each other when the spring H is forced outward by the roller 17. The end of the spring K has its motion in the direction toward the more 'or less, to adjust it and thereby to adjust the field of play of the spring K. The result of this construction is that the spring H may have a relatively light tension against the roller 17 as the latter first contacts with the inclined jaw 19' and then as the spring H 1s moved further in a lateral direction it comes into contact with and pushes laterally the spring K, thereby effectively closing the electric contact between H and K while at the same time the springs H and K may have a further outward movement together, so that they can yield as the roller 17 travels further between the spring jaws 19 and 19. This avoids the necessity for extremely accurate adjustment of the springs. When the electromagnet device is de-energized, the plungers B, B and their attached parts move outward, thus removing the roller 17 from between the jaws 19, 19.- The spring H moves back, by its own resiliency, toward the spring H, the spring K following spring H for a short distance, until stopped by its hooked end 22 engaging the stop L, whereupon it is no longer able to follow the spring H and the latter, in its further movement,

causes a separation of the contacts, thereby I armature and plungers being of breaking the electric circuit from K to H.

It will be noted that in the embodiment of the invention shown in the drawings the means forlimiting the play of the plungers is so adjusted that in the extreme outward position the faces of their tapered ends lie substantially in the same plane as the inner face of the yoke, or, at least, of that part of the yoke in the vicinity of the coils. Hence, the maximum power is applied to the plungers at starting, due to the concentration of the magnetic flux at the tapered ends of the plungers and at the inner face of the yoke adjacent the openings therein. At this position the square of the flux density divided by the equivalent area of the path is a maximum.

An important difference between this electromagnet device and plunger and solenoid devices heretofore employed .is that the latter applies the maximum pull on the plungers just beyond the center of the winding, whereas the present device applies its maximum power at a point in the plane'of the extreme outer end of the winding. Also, it is to be noted that the main armature plays an effective part when the plungers are in or approaching their innermost position.

What is claimed is:

- '1. An el'ectro-mag'net device comprising a yoke, an armature, at least two plungers, and at least two magnetizing coils, the yoke, magnetic material, said plungers being arranged to move within the respective coils in the direction of the longitudinal axes of the plungers, each plunger having its inner end tap-- ered for a distance not less than its diameter, said armature being joined to the outer ends of the plungers, said yoke having openings in line with the respective plungers, that part of the yoke intermediate said openings having a cross-sectional area not substantial- "ly less than the cross-sectional area of a requisite plunger of material of high permeability, and havingits dimension in the direction of the longitudinal. axes of the plungers at least as great as the diameter of such a plunger, and means for limiting the playof the plungers within the coils.

2. An electro-magnet device comprising a yoke, an armature, at least two plungers, and at least two magnetizing coils, the yoke,

I site plunger of material of ture and plungers messes armature and plungers being of magnetic material, said plungers being arranged to move within the res ective coils in the direction of the lon itudmal axes of the plungers, each plunger aving its inner end tapered for a distance not less than its diameter, said armature being joined to the outer ends of the plungers, said yoke having openings, in line with the of the-yoke intermediate said openings having a cross-sectional area not substantially less than the cross-sectional area of a requihigh'permeability, and having its dimension in the direction of the longitudinal axes of the plungers at least as great as the diameter of such a plunger, and means for preventing the plungers from moving outward beyond that position where respective plungers, that part the faces of the tapered ends are substantially in the plane of the inner face of the yoke. 3. An electro-magnet device comprislng a yoke, an armature, at least two plungers, and

at least two magnetizing coils, the yoke, armarial, said plungers being arranged to move within the respective coils in the direction of the longitudinal axes of the plungers, each plunger having its inner end tapered for a distance not less than its diameter, said armature being in the form of a relatively wide and thin plate joined to the outer ends of theplungers, said yoke having openings in line with the respective plungers, that part of the yoke intermediate said openings having a cross-sectional area not substantially less than the cross-sectional area of a requisite plunger of material of high permeability and its dimension in the direction of the longitudinal axes of the plungers at least as great as the diameter of a plunger, and means for limliting the play of the plungers within the 001 s.

4. An electro-magnet device, comprising a yoke, an armature, at least two plungers, and

comprising a stop-rod having ahead, a cup being of magnetic matecarried by the armature and having an opening through which the'stop-rod passes, and a felt washer surrounding the stop-rod and located between the cup and head, said cup -1 being made conical on its face toward the head, to receive the washer.

5. In an electro-magnet device, the combination, with the yoke, the plungers, the

magnetizing coils and the armature, of a stop device, a spring contact provided with a bent end arranged to engage the stop device to limit the movement'of said spring contact, a second spring contact arranged to be moved into contact with said first mentioned spring contact, and means moved by u the plungers for forcing the second spring contact against the first-mentioned spring contact.

6. .An electromagnetic device comprising a magnetic yoke, at least two coils carried by the yoke, core armatures arranged to move within said coils in the directions of the axes of the armatures, a connecting armature between the cores, whereby the coresand connecting armature move as a unit, spring contacts carried by the yoke and arranged between the coils, and a member carried by the connecting armature between the cores and adapted to cause the spring contacts to engage near the completion of the strokes of the armatures, the contacts acting as braking means to slow the movement of the core armature.

In testimony whereof, I have hereunto set -my hand.

ARLEIGH N. VAN NOSTRAND. 

